To a solution of 2-methylphenylzinc chloride ([84109-17-1], previously prepared from o-tolylmagnesium chloride (44.07 mL) and zinc chloride (8.81 g) in THF (200 mL)) a mixture of 4-trifluoromethanesulfonyloxy-5,6-dihydro-2H-pyridine-1,3-dicarboxylic acid 1-tert-butyl ester 3-methyl ester (CAS Reg. No. [161491-25-4]) (11.4 g) in THF (90 mL) followed by tetrakis(triphenylphosphine)palladium(0) (1.02 g) was added. The reaction mixture was stirred at room temperature over night and then was quenched with ice. The mixture was diluted with tert-butyl methyl ether and washed with 2 M aqueous sodium carbonate solution. The aqueous phases were extracted with tert-butyl methyl ether. The combined organic layers were washed with brine, dried (Na2SO4), filtered and evaporated. Purification by chromatography (SiO2, n-heptane/ethyl acetate 5:1) gave 4-o-tolyl-5,6-dihydro-2H-pyridine-1,3-dicarboxylic acid 1-tert-butyl ester 3-methyl ester as light yellow oil, MS: 332.0 ([M+H])+.
